Step stool



FIG. 1 is a front overhead perspective view of a step stool showing my new design;

FIG. 2 is a rear underneath perspective view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a rear elevational view thereof;

FIG. 7 is a top elevational view thereof;

FIG. 8 is a bottom elevational view thereof; and,

FIG. 9 is an enlarged perspective view of a portion thereof. 

CLAIM The ornamental design for a step stool, as shown and described. 